Sealed chuck assemblies of the type with which the present invention is concerned are usually generally cylindrical and have radially reciprocally movable jaw assemblies which include removable top jaws carried by master jaws mounted within a chuck body containing a jaw actuating mechanism. Such precision chuck assemblies often operate in hostile environments where fine chips and/or abrasive particles produced by associated machining operations are present and may enter a chuck causing moving parts of the chuck to wear prematurely, resulting in a loss of chucking accuracy and requiring chuck maintenance and/or part replacement. Such problems are a frequent source of costly machine down time and may result in poor workpiece quality or workpiece spoilage.
Heretofore, sealed chuck assemblies have been provided to control the aforesaid problem. At least one such chuck assembly, marketed by Micro Centric Corporation, New York, N.Y., is sealed by a rubber cover or boot which substantially surrounds the entire chuck body. However, this chuck cover is exposed to the risk of possible damage at all times. Any damage to the chuck cover which causes loss of sealing integrity will generally necessitate removal and replacement of the entire chuck cover.
Another machine tool chuck assembly of a sealed type has a hollow chuck body containing a jaw operating mechanism and a master jaws supported for movement within openings in the face of the chuck body. Removable top jaws releasably secured to the master jaws cooperate with annular seals mounted on the face of the chuck body to seal the openings in the face. The top jaws must usually be changed each time a new machine tool setup is made, thereby exposing the openings in the chuck body. Since top jaw changes are usually made with the chuck assembly mounted on an associated machine tool, the openings in the face of the chuck body are likely to be frequently exposed to entry of contaminants such as chips and/or airborne abrasive dust particles produced by normal operation of the machine. Such a sealed chuck assembly is illustrated and described in international application WO96/29170, published under the Patent Cooperation Treaty (PCT), Sep. 26, 1996.
Accordingly, it is the general aim of the present invention to provide an improved sealed chuck assembly of a type having movable master jaws, top jaws releasably secured to and carried by the master jaws, and seals which remain in sealed condition in all positions of the master jaws and when the top jaws are removed from the master jaws to facilitate jaw changes.